Heat transfer catheter with elastic fluid lumens

ABSTRACT

The heat exchange catheters comprise a catheter body having a heat exchange structure formed over a distal region thereof. Heat exchange structure comprises an elastic chamber or balloon which conforms closely to the catheter body when uninflated and which expands to enhance the available heat transfer surface when heat exchange medium is introduced. The elastic structures may consist of elastomeric sheets or membranes or may comprise non-distensible sheets or membranes having elastic elements in order to control expansion and contraction. Methods for fabrication and use are also disclosed.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of applicationSer. No. 09/872,818 (Attorney Docket No. 020878-000200), filed on May31, 2001, the full disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to medical apparatus andmethods. More particularly, the present invention relates to theconstruction and use of heat exchange catheters having elasticallyinflatable heat exchange surfaces.

[0004] Under ordinary circumstances, the thermoregulatory system of thehuman body maintains a near constant temperature of about 37° C. (98.6°F.), a temperature referred to as normothermia. For various reasons,however, a person may develop a body temperature that is below normaltemperature, a condition know as hypothermia, or a temperature that isabove normal temperature, a condition known as hyperthermia. Hypothermiaand hyperthermia are generally harmful, and if severe, the patient isgenerally treated to reverse the condition and return the patient tonormothermia. Accidental hypothermia significant enough to requiretreatment may occur in patients exposed to overwhelming cold stress inthe environment or whose thermoregulatory ability has been lessened dueto injury, illness or anesthesia. For example, this type of hypothermiasometimes occurs in patients suffering from trauma or as a complicationin patients undergoing surgery. Likewise, examples of hyperthemniainclude exposure to overwhelming exposure to hot environmentalstimulation, injury or illness, or complications of anesthesia.

[0005] In certain situations, however, hyperthermia and especiallyhypothermia may be desirable and may even be intentionally induced. Forinstance, hypothermia is generally recognized as being neuroprotective,and may, therefore, be induced in conjunction with treatments forischemic or hemorrhagic stroke, blood deprivation such as caused bycardiac arrest, intracerebral or intracranial hemorrhage, and head andspinal trauma. In each of these instances, damage to neural tissue mayoccur because of ischemia, increased intracranial pressure, edema orother processes, often resulting in a loss of cerebral function andpermanent neurological deficits. Intentionally induced hypothermia mayreduce or avoid the damage that would otherwise occur if the patienttemperature was normothennic or hyperthermic.

[0006] Other examples where hypothermia may be neuroprotective includeperiods of cardiac arrest in myocardial infarction and heart surgery,neurosurgical procedures such as aneurysm repair surgeries, endovascularaneurysm repair procedures, spinal surgeries, procedures where thepatient is at risk for brain, cardiac or spinal ischemia such as beatingheart by-pass surgery or any surgery where the blood supply to theheart, brain or spinal cord may be temporarily interrupted. Hypothermiahas also been found to be advantageous as a treatment to protect bothneural tissue and cardiac muscle tissue during or after a myocardialinfract (MI).

[0007] Body heating and cooling can be achieved in a variety of ways.Body heating is most simply achieved by wrapping a patient in blanketsand/or heated jackets in order to raise body temperature over time. Bodycooling can be similarly achieved using cooling jackets. The ability tocool patients using external cooling, however, is problematic. Inducedcooling will trigger a patient's thermoregulatory responses, causingpatient's body to generate more heat in order to maintain bodytemperature. It has also been found that external cooling can cause thepatient to “shiver,” and that shivering not only causes discomfort butalso induces the patient's body to generate still more heat in response.

[0008] In order to overcome the deficiencies of external body heatingand cooling, it has been proposed to heat or cool blood in a patient'scirculation, thus effecting an internal modification of bodytemperature. For example, it has been proposed to remove blood in apatient, e.g., from the inferior vena cava, externally heat or cool theblood, and then return the blood to patient circulation. Such externalcooling of patient blood is performed, for example, duringcardiopulmonary bypass surgery where the heart is stopped and the bloodis also oxygenated. Such external blood cooling, however, suffers from anumber of deficiencies. It is quite invasive to the patient, is damagingto the blood (causing significant hemolysis over time), generally mustbe performed in a sophisticated operating room and by highly trained andexpensive medical specialists, and can only be performed for up toseveral hours before it must be discontinued. Thus, external bloodheating or cooling is not appropriate for many circumstances.

[0009] Of particular interest to the present invention, an improvedmethod for adding or removing heat from patient circulation uses a heatexchange catheter placed in the bloodstream of a patient, as describedin U.S. Pat. No. 5,486,208 to Ginsburg, the complete disclosure of whichis incorporated herein by reference. The Ginsburg patent discloses amethod of controlling the temperature of a body by adding or removingheat to the blood by inserting a heat exchange catheter having a heatexchange region into the vascular system and exchanging heat between theheat exchange region and the blood to affect the temperature of apatient. One method disclosed for doing so includes inserting a catheterhaving a heat exchange region comprising a balloon into the vasculatureof a patient and circulating warm or cold heat exchange fluid throughthe balloon while the balloon is in contact with the blood. Otherpatents and applications describing heat exchange catheters are listedbelow.

[0010] Heretofore, the balloons of heat exchange catheters havegenerally been formed from polyethylene terephthalate (PET) and othersubstantially non-distensable materials, i.e., materials which areessentially non-elastic and do not stretch when the balloon is filledwith heat exchange medium. Distensible or elastomeric heat exchangestructures, however, may have certain advantages over non-distensibleheat exchange structures in many situations. For example, when theballoon is non-elastic, it needs to be folded or otherwise constrainedon the distal end of the heat exchange catheter in order to facilitateintroduction. After use and deflection prior to withdrawal, the heatexchange balloon becomes loose and floppy, rendering withdrawal of thecatheter more difficult. In its loose and floppy condition, it may bemore prone to damage upon withdrawal from the patient. Further,responsiveness to various ranges of pressures is sometimes an advantage,for example when pulsing or fluctuating motion desirable to inducemixing for enhanced heat exchange in flowing fluid such as blood. Thecontrol of size by control of pressure in the elastomeric heat exchangestructure may be an advantage, for example, when a range of heatexchange surface sized can be obtained for different sized patientsusing the same type of device by controlling the pressure of the heatexchange fluid. Moreover, manufacturing of heat exchange catheters withPET and other non-distensible balloon materials may be more difficultand expensive than manufacturing the device with elastomeric material.

[0011] For these reasons, it would be desirable to provide improved heatexchange catheters, and in particular improved balloon structures onsuch heat exchange catheters. Such balloon structures will preferablyconform closely to the exterior surface of the heat exchange catheterwhen introduced and will return to such a closely conformingconfiguration when withdrawn after use. Such balloon structures shouldprovide adequate or improved heat transfer characteristics when comparedwith the PET and other non-distensible balloon materials of prior art.Moreover, such balloon structures should be fabricated from materialswhich are bio-compatible and which induce little or no clot formation(are non-thrombogenic). At least some of these objectives will be met bythe inventions described hereinafter.

[0012] 2. Description of the Background Art

[0013] Patents and published applications assigned to the assignee ofthe present invention include U.S. Pat. Nos. 6,306,161; 6,264,679;6,231,594; 6,149,676; 6,149,673; 6,110,168; 5,989,238; 5,879,329; and5,837,003; U.S. Patent Publication US 2001/005791; and Published PCTApplications WO 01/64164; WO 01/58397; WO 01/152781; WO 01/43661; WO01/13809; WO 01/10323; WO 00/10494; WO 98/31312; and WO 98/26831. Otherpatents relating to body cooling include U.S. Pat. Nos. 6,325,818;6,312,452; 6,261,312; 6,254,626; 6,251,130; 6,251,129; 6,245,095;6,238,428; 6,235,048; 6,231,595; 6,224,624; 6,149,677; 6,096,068;6,042,559; 6,299,599; 6,290,717; 6,287,326; 6,165,207; 6,149,670;6,146,411; 6,126,684; 6,019,703; and 5,269,758. The full disclosures ofeach of these patents and published applications are incorporatedherein.

BRIEF SUMMARY OF THE INVENTION

[0014] This section describes what may be typical features andcharacteristics of a medical device of the invention, but unless thefeature is specifically stated to be necessary, the references are notlimiting of the invention despite their inclusion in this section.

[0015] The present invention provides improved heat exchange cathetershaving elastic heat exchange structures, referred to hereinafter as“balloons” or “chambers.” The heat exchange structures are elasticallyexpansible so that they inflate or enlarge when a suitable heat exchangemedium, such as heated or cooled saline, is introduced to the heatexchange structure under pressure. The heat exchange medium willusually, although not necessarily be non-compressible. Thepressure-induced expansion enlarges the heat exchange structure, thusincreasing the surface area of the heat exchange structure which isavailable for transferring heat to or from the circulating blood in apatient's vasculature.

[0016] Many aspects of the construction of the heat exchange cathetersmay be conventional and may, for example, incorporate many elements ofthe heat exchange catheters described in the patents and applications,which have been incorporated by reference above. For example, the heatexchange structures of the present invention will be incorporated on acatheter body having a proximal end, a distal region, and usually atleast two fluid flow lumens therethrough. The catheter body will besuitable for percutaneous introduction to the patient's vasculaturethrough a variety of access sites, such as introduction into the femoralvein and advancement into the inferior vena cave (IVC) or introductioninto one of the carotid veins or the subclavian vein and advancementinto the superior vena cava (SVC). Any other appropriate site may beused; for example placement in the arterial vasculature may be made byintroduction into the femoral artery and advancement into the aorta.Other placement as may be appropriate for the particular purpose iswithin the contemplation of this patent, for example into the renalarteries to cool the kidneys, into the hepatic arteries to cool theliver or into the carotid arteries to cool the bead or brain.

[0017] The catheter bodies will typically have a length in the rangefrom 15 cm to 100 cm, typically from 25 cm to 75 cm, and a diameter from1 mm to 4 mm, usually from 2 mm to 4 mm. The catheter bodies willtypically be formed from a relatively hard, non-elastic polymer,typically having a hardness in the range from 75 A to 82 D, usually from85 A to 72 D. Suitable polymeric materials include polyurethanes,C-Flex®, and the like. Specific catheter body designs are disclosed, forexample, in U.S. Pat. No. 6,264,679, assigned to the assignee in thepresent application, and WO 00/10494, the full disclosures which areincorporated herein by reference, as well as PCT applicationPCT/US01/03828, assigned to the assignee in the present application, andWO 00/10494, the full disclosures of which are incorporated herein byreference.

[0018] As used herein, the term “elastic” includes heat exchangestructures which are formed from a suitable elastomer, as well asstructures which are formed from non-elastomeric sheets or membranes andwhich incorporate elastic reinforcement or constraining materials sothat the structures may elastically expand and deflate as the heatexchange medium is introduced and removed. Suitable elastomers willusually be softer and often thinner than the material from which thecatheter body has been formed, but may be composed of the same polymericresin. Suitable elastomeric balloon or chamber materials will havehardness in the range from 65 A to 45 D, usually from 75 A to 100 A.Suitable elastomers include polyurethanes, silicone ruber, natural andsynthetic latex (although generally not preferred), polyvinyls,plastisized PVC and the like. An exemplary and presently preferredmaterial is styrene-ethylene-butylene-modified block copolymer withsilicone oil, available under the C-Flex® tradename. The use of a heatexchange structure material which is the same as (although softer andmore elastic than) the catheter body material is advantageous since itfacilitates heat sealing of the materials together, as will be describedin more detail below.

[0019] The catheter bodies of the heat exchange catheters of the presentinvention will usually have at least two lumens to provide for inflowand outflow of the heat exchange medium, respectively. Optionally,additional lumens may be provided for supply of heat exchange medium todifferent compartments within the heat exchange structure or for otherpurposes.

[0020] In a first aspect of the present invention, heat exchangecatheters comprise a catheter body having a proximal end and a distalend. A heat exchange balloon structure is disposed over the distalregion, and the balloon structure is constructed or composed of theelastic material selected so that the structure initially conforms tothe distal region of the catheter body (preferably without folding as ischaracteristic of non-distensible balloons such as angioplasty balloons)and expands elastically in response to the introduction of the heatexchange medium under pressure. When the treatment is done, and thesupply of the heat exchange medium terminated, the heat exchange balloonstructure will deflate elastically so that it again conforms to thecatheter body to facilitate removal of the catheter. While the heatexchange structures will be highly elastic, it will be appreciated thatsome hysteresis, i.e., loss of the elasticity, is acceptable. It ispreferred, however, that the elongation of the balloon structure in anyone direction be less than 10% after use, preferably being less than0.5%.

[0021] Preferred balloons and other heat exchange structures will berelatively small when deflated, having a diameter or width which doesnot significantly exceed that of round catheter body. The functionaldeflated cross-sectional size is sometimes called profile. If thecatheter is not round, this still gives a functional measure of the sizesince this is the size of puncture introducer hole that is necessary inorder to insert the catheter. Profile is generally measured in Frenchsize (Fr) with one Fr equal to 0.33 mm. The Fr size of the preferredcatheters including balloons will generally be between 4 Fr and 14 Frwith a size between about 6 Fr and 10 Fr being preferable. Generally, asmaller French size for insertion is preferable to a larger size, andone advantage of the elastomeric heat exchange region is the potentialof having a very large heat exchange surface when inflated despite asmall French size when deflated for insertion. When inflated at atypical heat exchange medium pressure in the range from 0.5 psig to 50psig, however, the heat exchange balloons or other structures will havea surface area which is significantly greater, typically increasing byat least 10% more typically by at least 25%.

[0022] In a second aspect of the present invention, the heat exchangecatheter comprises a catheter body having a proximal end, a distalregion, an inflow lumen, and an outflow lumen. The heat exchange balloonor other structure comprises a plurality of elastic polymer chambersdisposed over the distal region and fluidly connected at an inlet end tothe inflow lumen and at an outlet end to the outflow lumen. By dividingthe inflow of heat exchange medium among a plurality of heat exchangechambers, the heat transfer rate can be improved. Polymeric chambers maybe arranged axially, helically, or in other patterns over the distalregion of the catheter body. The number of chambers may vary, typicallybe in the range from two to twelve, usually from two to eight, andpreferably from four to eight. In order to further enhance heattransfer, it is sometimes desirable to circumferentially space-apart theaxial or spiral chambers which are formed over the distal region. Thesurface areas when inflated and deflated, material properties, and othercharacteristics of these catheters will generally be the same asdescribed with respect to the first embodiment of the catheter set forthabove.

[0023] In a third embodiment, a heat exchange catheter constructed inaccordance with the principles of the present invention comprises acatheter body having a proximal end, a distal region, an inflow lumen,and an outflow lumen. An elastomer tube (either consisting of anelastomeric material or reinforced or constrained by elastomericcomponents) is coaxially positioned over the distal region, and the tubeis sealed to the catheter body along a multiplicity of lines to defineat least one, and usually a plurality of separate inflatable chambers,each of which is fluidly connected at an inlet end to the inflow lumenand at an outlet end to the outflow lumen. The surface areas of thechambers, materials of the balloon and catheter body, catheterdimensions, and the like, may all be the same as described with thefirst and second embodiments of the present invention as set forthabove.

[0024] In a fourth aspect, the present invention comprises a method forfabricating a catheter. A tubular catheter body is first positioned overa mandrel where the catheter body has at least an inflow lumen and anoutflow lumen. An elastomer tube (as defined above) is placed over thedistal region of the catheter body, and the elastomer tube is thenattached to the catheter body in order to define a plurality ofseparate, elastically expandable chambers between the outside of thecatheter body and the inside of the elastomer tube. The chambers arearranged so that an inlet end of each chamber is fluidly connected tothe inflow lumen and an outlet end of each chamber is fluidly connectedto the outflow lumen. The dimensions, materials, and othercharacteristics of the catheter body and elastomer tube may generally bethe same as set forth above for the catheter body and elastic heatexchange region.

[0025] In the preferred embodiments, the elastomer tube is attached tothe catheter body using heat staking in which case it further preferredthat the elastomer tube be “heat sealable” with the material of thecatheter body, typically being the same material but having a differenthardness. By “heat sealable” it is meant that the materials of thecatheter body and the elastomer tube will, when exposed to heat, atleast partially melt and meld together along lines formed by a suitableheating tool. Such heat staking or other sealing will preferably beperformed over a multiplicity of lines to define the plurality ofchambers therebetween. Chambers may be formed axially, helically, or inother patterns as desired. In a preferred aspect of the fabricationmethod, the heat stake or other attachment lines will be formed to havea width in the circumferential direction in the range from 0.01 mm to 2mm, preferably from 0.1 mm to 0.5, in order to circumferentiallyseparate adjacent heat exchange chambers.

[0026] In a fifth aspect of the present invention, a method forexchanging heat with vascular circulation of a patient comprisespercutaneously introducing a catheter to a blood vessel of the patient.The catheter includes at least one elastic chamber conformed over asurface thereof while it is introduced. After introduction, the chamberis elastically inflated with a heat exchange medium, typically heated orcooled saline, whereby heat is exchanged between the heat exchangemedium and the vascular circulation. Typically, the catheter may beintroduced into a blood vessel, such as the femoral vein, an advanced sothat the heat exchange region is at a desired location in thevasculature such as the IVC. The heat exchange chamber is inflated withheat exchange medium at a pressure in the range from 0.5 psi to 50 psi,preferably from 1 psi to 30 psi, and a flow rate in the range from 5ml/min to 1000 m/min, preferably from 100 ml/min to 500 ml/min. Forheating, the temperature of the medium will typically be in the rangefrom 33° C. to 48° C., usually from 38° C. to 42° C. For cooling, thetemperature of the medium will typically be from −10° C. to 34° C.,usually from 0° C. to 10° C. In a particular aspect of the presentinvention, the heat exchange medium may be pulsed within the elasticheat exchange structure in order to cause the heat exchange surface tomove or pulse, as generally described in commonly assigned patentapplication Ser. No. 09/872,818, the full disclosure which haspreviously been incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a perspective illustration of a heat exchange catheterconstructed in accordance with the principles of the present invention.

[0028]FIGS. 2A and 2B illustrate a first embodiment of a heat exchangestructure according to the present invention.

[0029]FIGS. 3A and 3B illustrate a second embodiment of the heatexchange structure of the present invention.

[0030]FIGS. 4A and 4B illustrate a third embodiment of the heat exchangestructure of the present invention.

[0031]FIGS. 5A and 5B illustrate alternate cross-sectional views takenalong line 5-5 of FIG. 4B.

[0032] FIGS. 6A-6C illustrate a method of fabricating the heat exchangecatheters of the present invention.

[0033]FIG. 7 illustrates the heat exchange catheter of FIG. 1 being usedto treat a patient.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

[0034] Referring to FIG. 1, a heat exchange catheter 10 comprises acatheter body 12 having a proximal end 14 and a distal region 16. Thecatheter body 12 is a multi-lumen tube having the dimensions andcharacteristics set forth above. A hub 18 is attached at the proximalend 14 of the catheter body and includes an inlet port 20 and an outletport 22. The inlet port is fluidly connected to an inflow lumen 24 (FIG.2A) in the catheter body while the outlet port 22 is connected to anoutflow lumen 26. The inlet port 20 and outlet port 22 will typicallycomprise luer fittings or rather conventional attachments suitable forconnecting to a source of recirculating heat exchange medium, such asheated or cooled saline. Other suitable heat exchange medium may includesaline in other concentration, superoxygenated fluid, carbon dioxide,helium, water, or any other similar fluid that is non-toxic in case ofrupture in the heat exchange region. Suitable external heat exchangesources such as pumps and mechanical heat exchangers are described inthe patent and medical literature. See, for example, WO 01/64146, a PCTpublication whose applicant is the assignee of the present application.

[0035] A heat exchange structure, such as a helical elastic chamber 30is formed over the distal region 16 and fluidly connected to the inflowlumen 24 and outflow lumen 26, as best illustrated in FIGS. 2A and 2B.In its deflated state (FIG. 2A) the heat exchange structure 20 comprisesan elastomer tube having a closed distal end 32 which is tightlyconformed over the catheter body 12. The structure 30 will be sealed orstaked to the catheter body 12 along a line or multiplicity of lineswhich define the geometry of the structure when inflated, e.g., as ahelical structure as shown in FIGS. 1 and 2B. Other geometries willdescribed below.

[0036] Heat exchange medium will flow in through port 20 and lumen 24until reaching an open distal port 34 of the lumen. At this point, themedium inflates the heat exchange structure to create an expandedhelical chamber 36. The heat exchange medium then flows back in thedirection as shown by the arrows in FIG. 2B until reaching an outletport 38 which permits the medium to flow into the outlet lumen 26 andeventually out through outlet port 22. A plug 40 is provided at thedistal end of the outlet lumen 26 in order to prevent flow of the heatexchange medium in the wrong direction.

[0037] Although illustrated as a single spiral structure in FIGS. 1, 2A,2B, it will appreciated that the helical heat exchange structure maypreferably be formed as two or more parallel helical lumens. The use ofa plurality of lumens is generally preferred since it increases thetotal heat exchange area between the heat exchange medium and the bloodflowing through the vasculature.

[0038] While the heat exchange structures will preferably be formed froma tubular member attached over the outer surface of the distal region ofthe catheter body (to form the heat exchange volume between the othersurface of the catheter body and an inner surface of the tubularmember), in some instances it could be formed from a separate tube whichis wound or otherwise arranged over the catheter body 12, e.g., as shownin FIGS. 3A and 3B. An elastomer tube 42 can be inserted through a port38 and attached to the inner surface of lumen 26, as illustrated in FIG.3A. An opposite end of the tube 42 can then be inserted into the distalend of lumen 24 and attached, as also shown in FIG. 3A. Introduction ofheat exchange medium through lumen 24 will then expand the tube, asshown in FIG. 3B. Removal of the heat exchange medium, will, of course,result in the elastic tubes collapsing into their low profileconfiguration, again as shown in FIG. 3A.

[0039] A variety other configurations could also be employed. A simpleballoon structure without helical or other chambers formed therein isillustrated in FIGS. 4A and 4B. The structure of the catheter body 12remains the same, but an elastomer tube 50 is formed over the entirelength of the catheter body, as shown in FIG. 4A. By heat staking orotherwise sealing the tube over only a proximal portion of the catheterbody, a balloon may be fully inflated, as shown in FIG. 4B. Such fullinflation is shown in the cross-sectional view of FIG. 5A.Alternatively, the tube 50 could be axially heat staked or otherwisesealed to the catheter body, resulting in a multiple axial lobeembodiment as illustrated in the cross-sectional view of FIG. 5B. Aswith the helical embodiments, it will be desirable to heat stake orotherwise attach the elastomeric sheath along a line having a width W inthe ranges set forth above. In this way, the distances between each ofthe lobes 54 are circumferentially spaced apart to enhance heattransfer. In the embodiment of FIG. 5, pairs of inflow and outflowlumens 24 and 26 are provided for each of the pairs of lobes. Othermanifold means could be provided in order to interconnect the lobes inthe desired manner.

[0040] The preferred catheters of the present invention may befabricated according to the method illustrated in FIGS. 6A-6C. Thecatheter body 12 is placed over a plurality of mandrels 60, with onemandrel being provided for each internal lumen. At least one of themandrels 60 will be spaced in a proximal direction to permitintroduction of plug 40. An elastomer tube is then expanded and placedover the distal region 16 of the catheter body 12, as illustrated inFIG. 6A. Distal end 72 of the elastomer tube 70 is then closed andsealed, as shown in FIG. 6B. A heating unit 74 is then used to heatstake the elastomer tube 70 to the exterior surface of the catheter body12 allowing axial, spiral, or other desired lines in order to define thenumber and geometry of heat transfer chambers that is desired. Then themandrels are removed and the catheter is ready for final fabrication anduse.

[0041] Use of the catheter 10 for exchanging heat with patientcirculation and a blood vessel BV, as illustrated in FIG. 7. Thecatheter is percutaneously introduced to the target blood vessel, suchas the IVC, and proximal hub 18 (FIG. 1) attached to a suitable sourceof heat exchange medium, such as the heat exchange device illustrated inWO 01/64146, incorporated herein by reference previously. The heatexchange medium is introduced at a pressure and a flow rate in theranges generally described above so that the spiral heat exchangechamber 36 inflates. The inflation increases the available heat exchangearea, but does not cause the catheter to engage the blood vessel wallsand inhibit blood flow. Thus, blood flowing in the direction of arrows80 passes by the exterior of the spiral heat exchange structure 36, withheat transfer taking place between the structure and the blood. Theavailability of an elastic heat exchange structure permits some controlover the rate of heat transfer based on the pressure the flow rate ofthe heat exchange medium being introduced, and if the inflation ispulsitile, the rate of pulsation. For example, the amount of inflationmay be adjusted to optimize the heat exchange surface. If a largesurface with a high flow rate of the heat exchange fluid is desired tomaximize heat exchange, the pressure of the heat exchange fluid may beincreased. If the patient is small and a smaller heat exchange surfaceis desired because, for example, the vessel in which the heat exchangeregion is located is small, then lower pressure may be used to circulateheat exchange fluid. If a very small rate of heat exchange is desired,for example, if the patient is being maintained at a target temperature,then a very low inflation/circulation pressure may be used. It is alsotrue that heat exchange may be increased by pulsation of the heatexchange region. The rate of pulsation may be controlled to control therate of heat exchange.

[0042] The pressure and the rate of pulsation may be controlled byfeedback from either the patient or from the heat exchange fluid. Forexample, pressure feedback from the heart exchange fluid may be used tocontrol the pressure for the expansion of the heat exchange region.Alternatively, the expansion of the balloon may be controlled based onfeedback of the flow rate of the heat exchange fluid, patienttemperature, rate of change of patient temperature. Similarly the pulserate if any applied to the balloon may be controlled based on pressurefeedback, flow rate of heat exchange fluid, patient temperature, rate ofchange of patient temperature, and the like.

[0043] Another advantage to the ability of this catheter to expand underpressure might be to seal off a vessel where the balloon is located or aside branch over which the balloon is located. For example, it might beadvantageous to expand the heat exchange balloon sufficiently to blockflow through the vessel or into a side branch vessel in coordinationwith an intraaortic balloon pump. Similarly it might be advantageous totemporarily seal off a section of a patient's vasculature to helplocalize the application of certain drugs within the vasculature whileat the same time providing a heating or cooling balloon structure.

[0044] The embodiments set forth herein are merely exemplary of thesystems and methods of the present invention. Such exemplary methods arenot meant to be limiting, and it will be appreciated that a number ofmodifications and variations of the specific methods and structuresdescribed herein may be practiced within the scope of the invention asset forth in the claims below.

What is claimed is:
 1. A heat exchange catheter comprising: a catheterbody having a proximal end and a distal region; and a heat exchangeballoon structure disposed over the distal region; wherein the heatexchange balloon structure expands and deflates elastically whenuninflated.
 2. A heat exchange catheter as in claim 1, wherein the heatexchange balloon structure conforms without folding to the distal regionof the catheter body when uninflated.
 3. A heat exchange catheter as inclaim 1, wherein the heat exchange balloon structure has a diameter whenuninflated which does not exceed that of the catheter body.
 4. A heatexchange catheter as in claim 1, wherein the surface area of the heatexchange balloon structure increases by at least 10% when inflated byheat exchange medium at a pressure in the range from 0.5 psig to 50psig.
 5. A heat exchange catheter as in claim 1, wherein the catheterbody comprises a polymeric material having a hardness in the range from75 A to 80 D.
 6. A heat exchange catheter as in claim 4, wherein thecatheter body has a length in the range from 15 cm to 100 cm and adiameter in the range from 1 mrn to 4 mm.
 7. A heat exchange catheter asin any of claim 1 to 6, wherein the heat exchange balloon structurecomprises a polymeric material having a hardness in the range from 65 Ato 45 D.
 8. A heat exchange catheter as in claim 6, wherein thepolymeric material is selected from the group consisting ofpolyurethanes, silicone rubber, latex, polyvinyls, plasticized PVC, andstyrene-ethylene-butylene modified block copolymer with silicone oil. 9.A heat exchange catheter as in claim 7, wherein the catheter body andthe balloon comprise the same material having different hardnesses. 10.A heat exchange catheter as in claim 9, wherein the same material isselected from the group consisting of polyurethanes, silicone rubber,latex, polyvinyls, plasticized PVC, and styrene-ethylene-butylenemodified block copolymer with silicone oil.
 11. A heat exchange cathetercomprising: a catheter body having a proximal end, a distal region, aninflow lumen, and an outflow lumen; and a heat exchange balloonstructure comprising a plurality of elastic polymeric chambers disposedover the distal region and fluidly connected at an inlet end to theinflow lumen and at an outlet end to the outflow lumen.
 12. A heatexchange catheter as in claim 11, wherein the elastic polymeric chambersare arranged axially over the distal region.
 13. A heat exchangecatheter as in claim 11, wherein the elastic polymeric chambers arearranged spirally over the distal region.
 14. A heat exchange catheteras in any of claims 11-13, wherein the heat exchange balloon structurecomprises from two to twelve elongated chambers.
 15. A heat exchangecatheter as in claim 14, wherein the elongated chambers arecircumferentially spaced apart.
 16. A heat exchange catheter as in claim11, wherein the heat exchange balloon structure conforms without foldingto the distal region of the catheter body when uninflated.
 17. A heatexchange catheter as in claim 11, wherein the heat exchange balloonstructure has a diameter when uninflated which does not exceed that ofthe catheter body.
 18. A heat exchange catheter as in claim 11, whereinthe surface area of the heat exchange balloon structure increases by atleast 10% when inflated by heat exchange medium at a pressure in therange from 0.5 psig to 50 psig.
 19. A heat exchange catheter as in claim11, wherein the catheter body comprises a polymeric material having ahardness in the range from 75 A to 80 D.
 20. A heat exchange catheter asin claim 19, wherein the catheter body has a length in the range from 15cm to 100 cm and a diameter in the range from 1 mm to 4 mm.
 21. A heatexchange catheter as in any of claim 11 to 20, wherein the heat exchangeballoon structure comprises a polymeric material having a hardness inthe range from 65 A to 45 D.
 22. A heat exchange catheter as in claim21, wherein the catheter body and the balloon comprise the same materialhaving different hardnesses.
 23. A heat exchange catheter as in any ofclaim 11 to 12, wherein the heat exchange balloon structure comprises apolymeric material having a hardness in the range from 65 A to 45 D. 24.A heat exchange catheter comprising: a catheter body having a proximalend, a distal region, an inflow lumen, and an outflow lumen; and anelastomer tube coaxially positioned over the distal region; wherein theelastomer tube is sealed to the catheter body along a multiplicity oflines to define a plurality of separate inflatable chambers, each atwhich is fluidly connected at an inlet end to the inflow lumen and at anoutlet end to the outflow lumen.
 25. A heat exchange catheter as inclaim 24, wherein the inflatable chambers are arranged axially over thedistal region.
 26. A heat exchange catheter as in claim 24, wherein theinflatable chambers are arranged spirally over the distal region.
 27. Aheat exchange catheter as in claim 24, wherein the catheter comprisesfrom two to twelve inflatable chambers.
 28. A heat exchange catheter asin claim 27, wherein the inflatable chambers are circumferentiallyspaced apart.
 29. A heat exchange catheter as in claim 24, wherein theheat exchange balloon structure conforms without folding to the distalregion of the catheter body when uninflated.
 30. A heat exchangecatheter as in claim 24, wherein the heat exchange balloon structure hasa diameter when uninflated which does not exceed that of the catheterbody.
 31. A heat exchange catheter as in claim 24, wherein the surfacearea of the heat exchange balloon structure increases by at least 10%when inflated by heat exchange medium at a pressure in the range from0.5 psig to 50 psig.
 32. A heat exchange catheter as in claim 24,wherein the catheter body comprises a polymeric material having ahardness in the range from 75 A to 80 D.
 33. A heat exchange catheter asin claim 32, wherein the catheter body has a length in the range from 15cm to 100 cm and a diameter in the range from 1 mm to 4 mm.
 34. A heatexchange catheter as in any of claim 24 to 33, wherein the heat exchangeballoon structure comprises a polymeric material having a hardness inthe range from 65 A to 45 D.
 35. A heat exchange catheter as in claim 34wherein the catheter body and the elastomer tube comprise the samematerial having different hardnesses.
 36. A heat exchange catheter as inany of claim 24 to 33, wherein the heat exchange balloon structurecomprises a polymeric material having a hardness in the range from 65 Ato 45 D.
 37. A method for fabricating a catheter, said methodcomprising: positioning a tubular catheter body over a mandrel, whereinsaid catheter body has at least an inflow lumen and an outflow lumen;placing an elastomer tube over a distal region of the catheter body;attaching the elastomer tube to the tubular catheter body to define aplurality of separate elastically expandable chambers between theoutside of the catheter body and the inside of the elastomer tube,wherein an inlet end of the chamber is fluidly connected to the inflowlumen and an outlet end of the chamber is fluidly connected to theoutflow lumen.
 38. A method as in claim 37, wherein tubular catheterbody comprises a polymer having a hardness in the range from 75 A to 82D and the elastomer tube comprises an elastomer having a hardness in therange from 65 A to 45 D.
 39. A method as claim 38, wherein the polymeris selected from the group consisting of polyurethanes, silicone rubber,latex, polyvinyls, plasticized PVC, and styrene-ethylene-butylenemodified block copolymer with silicone oil and the elastomer is selectedfrom the group consisting of polyurethanes, silicone rubber, latex,polyvinyls, plasticized PVC, and styrene-ethylene-butylene modifiedblock copolymer with silicone oil (C-Flex®), polyurethanes.
 40. A methodas in claim 39, wherein the polymer and the elastomer are the samematerial but have different hardnesses.
 41. A method as in claim 37,wherein attaching comprises heat staking.
 42. A method as in claim 37 or41, wherein attaching comprises sealing along a multiplicity of lines todefine the chambers therebetween.
 43. A method as in claim 42, whereinthe lines are arranged axially.
 44. A method as in claim 42, wherein thelines are arranged spirally.
 45. A method as in claim 42, wherein thelines have a width in the range from 0.01 mm to 2 mm tocircumferentially separate adjacent chambers.
 46. A method forexchanging heat with vascular circulation of a patient, said methodcomprising; percutaneously introducing a catheter to a blood vessel ofthe patient, wherein the catheter includes at least one elastic chamberconformed over a surface thereof; elastically inflating the chamber witha heat exchange medium, whereby heat is exchanged between the heatexchange medium and the vascular circulation.
 47. A method as in claim46, wherein the catheter is introduced to a blood vessel selected fromthe group consisting of a. the inferior vena cava; b. the superior venacave; c. a jugular vein; d. a carotid artery; e. the aorta; and f. arenal artery.
 48. A method as in claim 46, wherein the at least onechamber is inflated with the heat exchange medium at a pressure in therange from 0.5 psig to 50 psig and a flow rate in the range from 5ml/min to 1000 ml/min.
 49. A method as in claim 46, wherein elasticallyinflating comprises pulsing the pressure of the heat exchange medium,whereby the surface of the elastic chamber moves in order to enhanceheat transfer.
 50. A method as in claim 46, wherein pressure feedbackfrom the pressure of the heat exchange fluid is used to control theexpansion of the heat exchange balloon.
 51. A method as in claim 46,wherein the flow rate feedback from the heat exchange fluid is used tocontrol the expansion of the balloon.
 52. A method as in claim 46,wherein the balloon is expanded to a sized based on the size of thevessel in which the heat exchange region is located.
 53. A method as inclaim 46, wherein the pulse rate of the expansion/deflation cycle iscontrolled to optimize heat exchange